1. Field of the Invention
The present invention relates to a cold rolling method for manufacturing a profile from a one-piece rolling stock in form of initial material with deforming regions of rolls which serve for deformation of the initial material.
2. Description of the Prior Art
Under a cold rolling process, one skilled in the art understands a process of deforming a one-piece rolling stock at a temperature below its recrystallization temperature with rolls.
Profiles produced from a rolling stock can have different shapes. With material-intensive profiles such as, e.g., C-shaped mounting rails, a main portion of the manufacturing costs in the cost of the material. Therefore, saving of the material results in a significant reduction of the manufacturing costs.
For structural reasons, a profile need not necessarily have a constant thickness, material thickness, over its circumference. Therefore, the less loaded sections of the profile can have a reduced thickness, which leads to saving of material.
A partial reduction of thickness by a single-step rolling, in a cold rolling process, of a strip-shaped rolling stock does not make sense. This is because of friction in a direction transverse to the roll and the stiffness of the flat rolling stock, the reduction of material is converted only into stretching in the longitudinal displacement direction and into hardening of the material. This leads to inner stresses and a noticeable wrapping of the rolling stock.
European Patent EP 0 259 479 B1 discloses a cold rolling process according to which an initial material is rolled in a plurality of stations between rotatable mandrels and rotatable pressure rolls which have, respectively, deforming regions inclined to a rotational axis of the rolls, whereby the thickness of the initial material is reduced, and the initial material widens in the direction of inclinations of the deforming regions. The reduction of thickness during the cold rolling process disclosed in the above-discussed European patent is analogous to that during a deep drawing process.
The drawback of the method or process, which was discussed above, consists in that the process enables a reduction of the number of necessary rolling stations in the rolling installation for forming a profile only for profiles having a trapezoidal cross-section.
Because of the inclination of the deforming regions, the pressure rolls have, in their deforming regions, different working diameters, which leads to wear and, thus, to undesirable marks in the profile.
Accordingly, an object of the present invention is a cold rolling process which would insure an improved widening of a one-piece rolling stock and an improved economic efficiency of the process.